This proposed Advanced Center For Interventions And Services Research "The Center for Prevention and Early Intervention", represents a collaborative effort between the Johns Hopkins University Bloomberg School of Public Health, our community partners in prevention and early intervention (the Baltimore City Public Schools System and the Maryland State Department of Education), and prevention and early intervention researchers at Morgan State University, Pennsylvania State University, the University of California at Los Angeles, the University of Alabama, Columbia University, and Stanford University. The overall mission of the Center is to carry out methodological and pilot and feasibility research to support evaluations of the effectiveness of evidence-based preventive and early interventions aimed at the reduction of aggressive/disruptive behavior in children. The Center plans to develop and subsequently evaluate with the effectiveness of an integrated approach to prevention and early intervention in the elementary school setting. This integrated approach features the nesting of indicated and treatment interventions within a universal preventive intervention. The specific aims of the Center are to: 1) Establish the infrastructure necessary to be a model of academic/community collaboration; 2) Improve the design and analysis of school-based, effectiveness studies through advances in statistical and economic methods development; 3) Conduct pilot and feasibility studies in preparation for effectiveness trials of the Center's intervention and assessment initiatives; and 4) Disseminate the knowledge gained in each of the above areas in order to improve prevention and early intervention research. The Center consists of 4 Cores. The Operations Core provides support to Center collaborators across the Cores in the areas of: administration, assessment, data management, and dissemination and training. The Research Methods Core is focused on the development and application of biostatistical and economic methods in support of the Center's intervention and assessment initiatives. The Principal Research Core provides the structure and support for pilot and feasibility studies aimed at setting the stage for elementary school-based, effectiveness trials of evidence-based prevention and early interventions and assessments. The Research Network Development Core focuses on the development of the infrastructure within the Baltimore City Public School System and the Maryland State Department of Education for carrying out state of the art prevention and early intervention research and evaluations. These 4 Cores will work in an integrated fashion to insure the realization of the Centers' aims.